Security readout for executives and security teams
Plain-English summary
Certain Juniper MX Series and EX9200 Series routers and switches can lose forwarding capacity when they receive a specific MPLS packet. Repeated packets can keep the affected forwarding card down, creating a denial-of-service risk for MPLS-enabled network paths.
Executive priority
Treat as a planned high-priority network maintenance item for affected MPLS infrastructure. It is not supported as an active-exploitation emergency by the supplied sources, but business impact can be material if core forwarding cards crash repeatedly.
Technical view
CVE-2021-0288 is an MPLS packet-processing flaw in Junos OS on MX and EX9200 devices with Trio-based MPCs or PFEs. The packet can crash an FPC, and continued receipt sustains the DoS. Affected releases span 17.3 through 20.4 before the fixed maintenance releases listed by Juniper.
Likely exposure
Exposure is limited to Juniper MX Series and EX9200 Series systems using Trio-based forwarding hardware and affected Junos OS versions. The CVSS vector is adjacent network, so practical risk depends on where MPLS traffic can reach the device.
Exploitation context
The provided sources do not show active exploitation, and the CVE is not listed as KEV. The issue is still operationally important because it targets router forwarding components and can sustain a denial-of-service condition while malicious packets continue.
Researcher notes
Do not broaden scope beyond MX Series and EX9200 Series with Trio-based PFEs. The source bundle names fixed release thresholds but does not include packet details, exploit indicators, or standalone workarounds.
Mitigation direction
- Identify MX and EX9200 systems with Trio-based PFEs or MPCs.
- Upgrade Junos OS to a fixed release listed in Juniper JSA11190.
- Prioritize devices carrying MPLS traffic or supporting critical network paths.
- If patch timing is constrained, check Juniper guidance for supported interim controls.
Validation and detection
- Inventory Junos OS versions against the affected release ranges.
- Confirm whether devices use Trio-based PFEs or MPCs.
- Review FPC crash logs and MPLS-related instability around reported outage windows.
- Verify upgraded devices run the fixed Junos maintenance release or later.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
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Open ATT&CK lookupCVE-2021-0288 mapping review
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Open ATT&CK lookup- Severity
- Medium
- CVSS
- 6.5 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H2.83.6Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
6.5MediumVector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://kb.juniper.net/JSA11190CVE reference · x_refsource_CONFIRM
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Improper Check for Unusual or Exceptional Conditions
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